Aerogel mesh getter

ABSTRACT

A porous light-weight getter which collects particulate and molecular contaminates that is believed a significant improvement over the prior art is provided in which a metal mesh matrix is coated with a low-density porous aerogel. In the prior art bare metal mesh matrices have been employed as getters, which are subject to ablation from high-velocity contaminant particles. In the composite getter of the present invention, the low-density aerogel coating protects the enclosed metal matrix from ablation and also can attract and hold the incoming high-velocity particle. On its part, the metal mesh provides reinforcing support to the aerogel covering and also good thermal conductivity therein so that such covering can be cooled to the low temperatures that attract such contaminants. The invention further provides method for manufacture of the composite getters of the invention. Such composite getters are useful in decontamination in semiconductor manufacturing processes and storage thereof and in decontaminating optical systems including a space-based telescope. 
     In other embodiments, the getter of the invention can be mounted in air ducts to serve as a filter therefor, can be mounted in a photocopier for capture of toner fog, can be mounted in areas of semiconductor manufacturing for collecting contaminates proximate thereto, can be mounted in operating rooms, cleanrooms, in storage areas for surgical instruments, in spacecraft and the like for decontamination thereof.

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or forthe Government for governmental purposes without the payment of anyroyalty thereon.

This application is a division of application Ser. No. 07/981,923, filedNov. 12, 1992, now U.S. Pat. No. 5,308,533 which in turn is acontinuation-in-part of application Ser. No. 07/800,817 filed Nov. 29,1991 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a lightweight getter for contaminants,particularly an aerogel mesh getter therefor.

2. The Prior Art

Optical sensors in space-based astronomical observatories and otherobservation satellites are often required to detect low-radiance objectsagainst relatively bright backgrounds such as the Earth and the sun.This requires that the optical system have a high out-of-field-of-viewrejection capability and thus low scatter optical surfaces (mirrors andlenses). Launch, deployment and satellite operations such as gimbalmotions create vibration-induced contaminants which have a highprobability of becoming attached to optical surfaces or accumulating inthe sensor's field of view. Propulsion effluents, nonmetallic materialoutgasing and the natural space environment also produce contaminantsthat can deposit onto surfaces sensitive thereto such as lenses, mirrorsand solar collectors.

To alleviate the above surface contamination problem, certain deviceshave been developed which direct a spray, jet or beam at a surface todislodge the contaminant particles therefrom. This is, e.g. a gas-soldsnow mixture spray or ion beams are applied to remove contaminants fromthe optical surfaces. However, one removed from such surface, thesespecies must be collected to prevent their re-deposition on an opticalsurface and/or their floating in the field of view of an opticalinstrument.

In the prior art, collectors known as "getters" have been employed forthe purpose of collection or capture of the above contaminants. Theseprior art getters have taken the form of one or more layers of metalmesh, charged plates and charged dielectric plates (electrets). Howeverthe metal mesh device, e.g., of aluminum alloy, are brittle and havedesorption rates and ablation tendencies. The charged plates requirekilovolts of charge which is unacceptable for a satellite due to, e.g.arcing problems in space. The charged dielectric plates have captureradii too low to be useful in practice.

Further, high performance optical and micro electronic components haveever tightening contamination specifications placed upon them.Contamination is now seen as a major reason for the degradation of spacebased optical systems and failure of high density integrated circuitsused through industrial and military systems. Contamination is currentlycontrolled by the use of cleanrooms, process monitors and manualcleaning techniques which include solvent wipes, strippable coatings,wet-dry processes, ultrasonics and air purges. The major disadvantagesof these techniques are their inability to remove submicron particlesand the potential of leaving molecular residues on the cleaned surfaces.Some of these cleaning techniques can be damaging to delicate surfacesand/or have toxic waste products; for, e.g. biomedical applications suchas virology research laboratories.

To address the above contaminant problem, certain contamination removaland collection techniques have been attempted in the prior art. However,some of these removal techniques create a flux of removed contaminateswhich can then re-deposit on clean surfaces or be ejected into theenvironment. Current collection devices, such as filters, charged metalplates and screens and charged dielectrics have collection efficienciesand capture radii incommensurate with the new nano-scale semiconductordevices, optical systems and biomedical cleanliness requirements.

Accordingly, there is a need and market for a contaminant getter that iseffective and otherwise obviates the above prior art shortcomings.

There has now been discovered a lightweight contaminant getter thatcollects and holds particulate and molecular contaminants without theabove-noted high voltage and ablation problems.

SUMMARY OF THE INVENTION

Broadly, the present invention provides a porous lightweight getterwhich collects particulate and molecular components comprising, a metalmesh matrix and a low-density, porous, aerogel coated on said matrix.

The aerogel collects and contains the above contaminants while the metalmesh provides support for such aerogel and a thermally conductive pathby which such getter can be maintained at a desired temperature forcollection purposes.

Also provided is a method for forming a composite getter which collectsand holds comtaminants comprising covering a metal mesh matrix with anaerogel.

Further provided is a method for preparing a lightweight getter whichcollects contaminants comprising condensing an aerogel precursor oil,e.g. a silica oil onto a metal mesh substrate, catalyzing said oil toform a gel and extracting solvent from said gel to dry same to a silicaaerogel, to form a getter with a porous low-density aerogel covering ona metal mesh matrix.

By "low density" aerogel, as used herein, is meant a) aerogel having adensity of from 1 to 10 mg/cc (ULD aerogel) and b) aerogel having adensity of from 10 to 500 mg/cc (LD aerogel).

By "covering" the metal mesh matrix, as used herein, is meant coating orencapsulating such matrix with an aerogel.

By "coating" such matrix is meant applying a surface aerogel layerthereon, e.g. per FIG. 5, hereof.

By "encapsulating" such matrix is meant applying said aerogel throughoutand on such matrix, e.g. per FIG. 6 hereof.

By "AMCC" as used herein, is meant Aerogel Mesh Contamination Collectorof the invention. It includes a stand alone device which acts as a"flypaper" type collector. The AMCC can have arbitrary geometric shapesand topological and morphological natures depending on function.

By "AMCC/CRS" as used herein, is meant the above AMCC in a configurationwith a Contamination Removal System, e.g. a solid gas jet spray or ioncleaner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more apparent from the following detailedspecification and drawings in which;

FIG. 1 is a perspective view of an optical instrument which houses acollector or getter either of the prior art or of the present invention;

FIG. 2 is a fragmentary sectional elevation view schematic of acontaminant dislodging apparatus for a substrate;

FIG. 3 is a plan view of mesh sections of getters of the prior art;

FIG. 4 is a plan view of a section of a contaminant getter according tothe present invention which can be employed in the optical instrumentshown in FIG. 1;

FIG. 5 is a perspective view of a composite getter according to thepresent invention;

FIG. 6 is a perspective view of another composite getter embodying thepresent invention.

FIG. 7 is a sectional elevation, schematic view of a decontaminantfilter system embodiment of the invention;

FIG. 8 is a sectional elevation schematic view of another decontaminantfilter system embodiment of the invention;

FIG. 9 is an isometric schematic view of another composite getterdecontamination system embodiment of the invention;

FIG. 10 is a sectional elevation schematic view of yet another compositegetter decontamination system embodiment of the invention;

FIG. 11 is a perspective schematic view of still another compositegetter decontamination system embodiment of the invention and

FIG. 12 is a perspective schematic view of a contaminate removal andcomposite getter, decontamination system embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring in more detail to the drawings, a space-based telescope 10having a barrel 12, cover 14, primary optical component, e.g. mirror 16,having cleaning jets 20, and annular collector or getter 22, are mountedin the telescope barrel 12, as shown in FIG. 1. This telescope system isknown in the prior art.

As shown in FIG. 2, the mirror 16 of the above telescope employscleaning nozzles or jets 20, which direct a solid/gas jet spray ofsnowflakes 24 against contaminant particles 26, to dislodge them fromthe surface of such mirror 16, as shown in FIG. 2. The so-dislodgedparticles 26 are then supposed to be captured by the getter 22 of FIG.1.

Prior art getters which have been discussed above, have includedaluminum alloy mesh sections such as mesh section 30, having ten poresper inch, mesh section 32, having 20 pores per inch and mesh section 34,having 40 pores per inch, as shown in FIG. 3.

As noted previously, the above aluminum alloy mesh getters are brittle,are subject to desorption of the captured particles and are subject toablation upon collision therewith by the so-dislodged particles. Thatis, as shown in FIG. 3, particle 31, upon collision with getter meshsection 34 causes ablation and launching of two aluminum mesh particles33 and 35 as shown. Thus the capture and retention rate of contaminantparticle (and molecules) by prior art getters is unacceptably low andmany of these non-captured particles can redeposit on optical componentsor float in the optical sensor's field of view.

To alleviate the above problems, the getter of the present invention isprovided. That is, a low-density, porous material is coated onto a metalmesh section to provide an improved contaminant getter according to theinvention. For example, as shown in FIG. 4, metal mesh section 40 has anultra-low density (ULD) silica aerogel condensed thereon to provide aneffective and improved getter according to the present invention, whichattracts and holds contaminant particles or molecules, thus enhancingthe contaminant cleaning process, e.g. in an optical telescope such asshown in FIG. 1.

In FIG. 1 is also shown an electron gun 18 which (by electron beam 19)is used to sputter molecular contaminants from optical surfaces. Also,the jet spray nozzles 20 direct snowflakes within a gas stream at thesubstrate 16, per FIG. 2, to remove contaminate particles. As thecomtaminants are removed from the optical surface, they are attracted toand held by the getter 22 of the invention, as shown in FIG. 2.

Also, as shown in FIG. 1, a coolant line 25 (for, e.g. liquid N₂)divides into cooling branch lines 27 and 29, as shown in FIG. 1. Coolantline 29 connects with and cools primary mirror 16 while coolant branchline 27 connects with and cools getter 22 as shown in FIG. 1 andindicated in FIGS. 2, 5 and 6. The getter may also be cooled using acryocooler by means known in the art.

The metal mesh segment of the invention is shown in two embodiments inFIGS. 5 and 6. Thus metal mesh block 44 has coolant branch line 27running therethrough and is coated on its exterior surfaces with layersof silica aerogel, i.e. layers 46, 48 and 50 as shown in FIG. 5.

Alternatively another composite getter embodiment of the invention isshown in FIG. 6 wherein the metal mesh block 52 (which has coolant feedline 27 running therethrough) is encapsulated or coated throughout aswell as on the exterior surfaces thereof) with low density silicaaerogel 54, as shown in FIG. 6.

In either embodiment a getter surface coated with low density (includingULD) aerogel is presented to an oncoming particle which can collide withand imbed itself into the aerogel covering at the surface of the getteror below the surface thereof.

As noted above, the aerogel covering protects the metal mesh core orsubstrate thereunder from ablation upon impact by a fast-movingcontaminant particle or molecule. At the same time the metal mesh core,e.g. mesh 44 of FIG. 5 or mesh 52 of FIG. 6, provides good thermalconductivity to the coolant feed line 27 and thus enable the fastcooling of the aerogel coating of the respective composite getter, thebetter to attract contaminants to the getter.

Thus the getter of the present invention is a fusion of a suitable metalmesh with a low density cellular foam, e.g. a silica aerogel having apreferred density of 3-30 mg/cc.

The components of the getter of the invention e.g. shown in FIGS. 4 and6 complement each other in that the aerogel is flexible, hydrophilic,porous and has a high compliance tensor in low temperature environments.Aerogel also coats and protects the metal mesh from ablation uponparticle impact, and attracts and holds such contaminant and preventsits redeposition on an optical surface. On its part, the metal meshprovides a reinforcing element to the aerogel covering and such meshprovides good thermal conductivity within such covering. This isimportant because a cold getter better attracts contaminants and themetal mesh's thermal conductivity serves to maintain the aerogelcovering as cool as desired, e.g. in an optical instrument forattraction of contaminant particles or molecules.

A word about the method for preparing ULD silica aerogel employed in thegetter of the present invention. While such method is not part of thepresent invention, the end product is and accordingly such method isbriefly discussed. This is because the ULD aerogel employed in thegetter of the present invention is different from more conventionalaerogels which have greater density and thus greater weight, lowerporosity, and lower particle absorption capability.

Conventional silica aerogel employs the hydrolysis and condensation oftetraethoxysilane (TEOS) and/or tetramethoxysilane (TMOS) to producegels which are then supercritically extracted to a low-density siliconglass network. This single-step solgel process has been used for severalyears in producing materials with densities ranging from 20 to 1100mg/cc. This method is suitable for preparing LD aerogels employed in thepresent invention. However, such method requires high temperatures, e.g.400° C. and pressures, e.g. 300 bars and certain precautions may berequired.

The present invention employs an aerogel preferably made by a two-stepextraction process. The two-step process differs from a conventionalsolgel process in that it generally proceeds at lower temperatures andpressures than the above one-step process and instead of requiring anextremely dilute solution to gel as in the single-step reaction, apartially hydrolyzed, partially condensed polysilicate mixture isprepared from which the alcohol is replaced as the solvent and then thisnon-alcoholic solvent is supercritically extracted.

That is, the solvent replacement technique employs liquid carbondioxide, CO₂, to purge the system of the alcohols and thensupercritically extracts the replacement solvent, i.e. heats the systemto a relatively low 40° C., (and e.g. 40 bars pressure) to drive off theCO₂. This leaves a very low density silicon dioxide network or aerogel,with densities ranging from 1-900 mg/cc.

In a more specific example, an aerogel getter of the invention isfabricated using the above technology by first preparing a condensedsilica oil by reacting TMOS with a sub-stoichiometric amount of water inmethanol, under acidic conditions, with the following molar ratios:

    1 TMOS:1.3 H.sub.2 O: 2.4 MeOH: 10 HCl.

This mixture is then distilled, removing much of the methanol andleaving the silica oil (which includes the TMOS). The oil is thenhydrolyzed:

    1 TMOS: 4.0 H.sub.2 O

This reaction is done in a pyrex glass mold in the presence of anon-alcoholic basic diluent (NH₄ OH). Also present in the glass mold isa metal mesh and a catalyst (referenced below). Gel times vary from12-72 hours. The silica aerogel is obtained from this "alcogel" by usingliquid carbon dioxide to purge the alcogel of alcohol and replace itwith such liquid carbon dioxide (which keeps the aerogel pores open).Thereafter heat is applied to raise the temperature of such aerogel toabout 40° C., to apply super-critical triple point extraction (CO₂ phasediagram) to drive off such replacement solvent in the autoclave. Thetemperature is ramped (up to about 40° C.) while pressure is controlledand when finished, the autoclave (and the dried porous aerogel) ispurged with dry nitrogen. The aerogel-coated mesh or getter of theinvention is then removed from the mold for testing, storage or for usein decontamination of optics.

For more information on the above two-step extraction process or solventreplacement technique, in preparing aerogels, see an article by LaurenceHrubish and Thomas Tillotson in a book entitled "Better Ceramics throughChemistry Part IV," Materials Research Society, MRS Press, PittsburghPa., 1991, which article is incorporated herein by reference.

In an example of fabricating a composite getter, according to thepresent invention, an aluminum alloy mesh at e.g. 10 pores per inch, isplaced in a pyrex glass mold in an autoclave and covered with a solutionof TMOS and undergoes the above-mentioned hydrolysis and condensationreactions in the presence of a catalyst as more fully described in theabove-cited publication. A gel forms around the wire mesh and the gelundergoes a two-step solvent extraction process in which methanol isreplaced by liquid carbon dioxide as an intermediate solvent as notedabove. The liquid carbon dioxide is then supercritically extracted usingthe triple-point (phase diagram) drying technique. The pH andsolvent/solute mixing ratios are set to achieve aerogel densities on theorder of 3-30 mg/cc. The autoclave is then purged with dry nitrogen asdiscussed above and the composite getter of the invention obtained.

As indicated above, the aerogel employed in the getter of the inventionis suitably a silica aerogel which has been extracted to a low-densitysilica porous glass network. However other low density aerogels can beemployed within the scope of the invention, including inorganics fromthe Periodic Table of The Elements, e.g. aerogels of SiC, CaF or Be andincluding organics, e.g., aerogels of resorcinol-formaldehyde and ofmelamine-formaldehyde.

The aerogel employed in the getter of the present invention has adensity ranging from 3-900 mg/cc and preferably from 3-30 mg/cc.

The metal mesh components used in the composite getter of the presentinvention can be of aluminum alloy mesh or other metal mesh and can havepore sizes ranging from 5-100 pores per inch. Such metal mesh can be,e.g. coated with aerogel, per the invention, to form a coating thereon,e.g. of 30 to 500 microns thick.

The getter of the invention can be made in various shapes, e.g. annularas shown in FIG. 1 or other suitable shape and can be employed indecontamination of optical or other systems, on land, sea, in the airand preferably in space applications.

The composite getter of invention is suitable for use in 1)contamination prevention of small and large optical systems includingtelescopes, interplanetary and solar explorers and space stations, 2)contamination prevention for ground-based systems and components whetherin clean rooms, test chambers, storage, transportation or operation, aswell as 3) in semiconductor processing operations.

The composite getter of the invention serves also to collect and containparticulate and molecular contaminants in order to prevent theirdeposition onto sensitive optical surfaces during testing, storage,transportation, launch, deployment and operation of sensor systems. Thephysics of low dennsity aerogels compensates for the shortcomings ofmetal mesh getters and is believed to represent a significant advance ingetter design.

The composite getter of the invention is coated with a low-density,porous aerogel that, as noted above, has a high-compliance tensor inlow-temperature environments. That is, the aerogel coating has asomewhat flexible surface so that upon being struck by a high-velocityparticle, the surface will tend to liquify or soften and admit theparticle and then hold it. In the prior art such high-velocity particleon impact, e.g. with a metal mesh getter, fractures and ablates thesurface thereof, causing the formation of additional contaminantparticles in the system.

In addition to the space-based application described above, the aerogelgetter of the invention can be used with ground-based space simulationchambers during vacuum and vacuum cryogenic optical testing. It may alsobe placed inside of optical storage and transportation vessels as wellas at semiconductor manufacturing and processing locations, to maintainrequired cleanliness levels.

In further embodiments of the invention, the AMCC embodying theinvention, can be employed as air filters in, e.g. hospital rooms, ascollectors and filters for environments in which virus and diseasemolecules can become airborne threats as aerosols. Such filters, whichcan also serve molecular sieves, are applicable to HIV hospital careunits and biomedical research laboratories.

Thus per FIG. 7, in an air duct system 60 in, e.g. an operating room ora medical lab, circulating fan 62 pulls aerosol laden air into such duct60 and through the AMCC 66 of the invention and removes, filters out orentraps, e.g. virus and disease molecules or other contaminants,outputting cleaner air 68, as shown in FIG. 7.

Such embodiment of the invention can find use in other applications.These applications include use in electronics medical equipment fanfilters. In these high probability of hazardous aerosol typeenvironments, electronic instrumentation, most of which contains smallcooling fans, creates air currents. Airborne contaminants are swept upin air currents created by these fans, to be scattered. Aerogel meshfilters (or AMCCs) for these fans, would not only act as molecularsieves but also chemically bond, e.g. to viral species.

In another embodiment, a gas purifying and collection system 7,employing an AMCC sieve of the invention, is shown in FIG. 8. Here abottle 72 of semi-purified gas, e.g. silane gas having silica particlestherein, feeds through valve 74, pipeline 76, AMCC 78 and valve 80 intostorage in a vacuum bottle 82, as shown in FIG. 8. Here the aerogel meshfilter of the invention (AMCC) collects the solid silica particles,and/or molecules, passing a purified silane gas into the vacuum bottle82, as indicated in FIG. 8.

Thus the system of FIG. 8 can be employed for providing high quality gasi.e. SiH₄, which gas is filtered by the AMCC of the invention, e.g. toremove SiO_(x) particles and water molecules (which can condense in thegas line 76 of FIG. 8) and obtain a purified silane gas in the vacuumchamber 82 for use in fabricating silica thin films and semiconductorsin a high purity environment.

Such purifier systems embodiment of the invention can be employedbiotechnically to pass aerosols of micro-organisms through suchdecontamination system 70 and through the AMCC 78 which, dependent uponpore size (of the aerogel mesh filter), will pass smaller molecules ormicro-organisms and prevent larger molecules or micro-organisms fromentering the vacuum chamber 82, as indicated in FIG. 8 hereof.Accordingly, this embodiment of the invention provides a biotechnologyfilter for micro-organism (or other particle) sizing within the scope ofthe invention.

The AMCC of the invention also finds application in an ICnano-fabrication or microfabrication mask aligner and UV exposer. Inthis apparatus, a high precision microcircuit is lithographed by largescale mechanical motion in a robotic system. IC features at submicrondimensions are created. At the same time, the robotic motion of thesystem creates aerosols of particulate and molecular species atsubmicron spatial dimension (as a colloid's inertia is characterized byBrownian motion). Also, the UV light employed in such apparatus canphotopolymerize these aerosol particles. Accordingly, severalstrategically placed AMCCs are required herein to obviate the abovemicro and nano contamination threat.

Thus with reference to FIG. 9, mask fabrication apparatus 86 has stage88 which supports a photographic plate 900 under mask 92, in turn underUV lamp 94, as shown in FIG. 9. On such stage 88, 3 AMCCs 95, 96 and 97are positioned around the plate 90, mask 92 and UV lamp 94, as shown inFIG. 9. As always, the AMCCs are maintained at low temperature toattract decontaminants, including aerosols of particulate and molecularspecies emanating from the motion of the robotic system (not shown).

In another embodiment, in offices and print shops, the AMCC embodyingthe invention is advantageously employed. Thus in photocopiers, FAXmachines and computer printers, the black carbon-base toner is aconstant source of airborne contamination which collects on the interiorsurfaces of these machines. The insertion of one or more embodiments ofthe AMCC of the invention, in various suitable shapes, inside thesemachines, provides a means to collect, e.g. toner fog (carbon or driedpaint particles in air), serves to prolong copier use time betweenfailure and makes for cleaner air quality in the room or office housingthese machines.

The AMCC embodying the invention also finds needed use as on-chipgetters. That is, in semiconductors today, the microchip offgases andconventional silica gel getters, collect and contain contaminants (e.g.water) up to approximately 150° C. Aerogel mesh heterostructure in theAMCC of the invention can collect and contain contaminants attemperatures reaching 300° C. before offgassing. This is believed asignificant advance in the state of the art when such AMCCs are usedwith microchips, which translates into an increased lifetime and hencehigher reliability of microchip circuits.

Thus in one embodiment the microchip assembly or circuit board 100, hasAMCC or getter 102, mounted upright proximate microchip 104 and hasupright getter 106, mounted proximate microchip 108, as shown in FIG.10.

In a related embodiment, microchip assembly or circuit board 110, hasAMCC of the invention or getter 112 mounted thereover within clearthermoplastic housing 114 as shown in FIG. 11.

Another embodiment of the invention is the AMCC/CRS which can remove aswell as collect contaminants over a wide temperature range in vacuum orambient environments. As noted above, CRS means contamination removalsystem. One embodiment of such a system is shown in FIG. 2 and hasalready been discussed above.

Another AMCC/CRS embodiment of the invention is shown in FIG. 12 whereinopen-ended waste container 120 has mounted therein a helically woundgetter 122. Also as shown in FIG. 12, a jet spray or ion beam gun 124(known in the prior art) directs, e.g. a spray of air and snow flakes126, at an IC substrate or chip 128. The spray removes contaminants fromsuch substrate and directs them into the waste container 120 where suchcontaminants of particles and/or molecules are mostly collected by thegetter 122 therein, the decontaminated or less contaminated spray 127,exiting the waste container 120 as shown or indicated in FIG. 12.

The above contaminant removal and collection system embodiment of theinvention, can be employed for cleaning of wafers and circuits thereof,the wafer holder, the process chamber and vacuum chuck cleaning as well.Further applications of the above contaminant removal and collectionsystem include the cleaning of:

a) semiconductor wafers prior to and following processing,

b) deposition chambers and all equipment used for semiconductorprocessing,

c) any coating pre-processing operations, such as painting preparationswhere particulates in the air as well as the environment, can causesignificant part reject rates and

d) hospital operating rooms in which surgical implements, surfaces (e.g.table tops) and instrumentation may be cleaned down to the micron sizedcontaminant level.

Other use seen for the getter embodying the invention include:

a) underground waste dumps. Here radioactive waste can react with thealkalai halides. The getter of the invention can be employed to collectand contain these species for further study.

b) hazardous waste incinerators and smoke stacks: the getter of theinvention can be used as a collector in various stages of incineratorsand smoke stacks and species collected for laboratory study and

c) in various mechanical systems with moving parts wherein acontamination free environment is required: for example, a cryocooler(used in spacecraft systems) in which moving parts create contaminantswhich eventually degrade performance. A small aerogel mesh getter of theinvention can alleviate this contamination source and extend the missionlifetime of the spacecraft and tactical sensor systems usingcryocoolers.

In an operating room or cleanroom, or in a room containing paint vapors,one can advantageously use the fan filter assembly of FIG. 7 and the jetspray-waste container system of FIG. 12, for thorough decontaminationthereof.

Thus in the embodiments discussed above, the effectiveness ofApplicants' getter embodiments are shown, e.g. for decontaminatingmetal, glass, ceramic, semiconductor and polymer substrates. This systemapplies to both cleanroom and cryogenic-vacuum conditions such asspacecraft environments. In addition the AMCC or getter can be used in astand alone configuration in which it collects contaminants in"flypaper" fashion or as a gas/air filtration system. The getter of theinvention is believed an advance in the state of the art gettertechnology because it can collect and contain both molecular andparticulate contaminants over a wide temperature range. Additionally,the AMCC/CRS embodiments of the invention can remove as well as collectand contain contaminants over a wide temperature range, in vacuum orambient conditions.

Thus the above getter embodiments of the invention find application in,e.g. semiconductor processing, biomedical laboratores, hospitaloperating rooms, computers and electronic equipment, office and printingequipment, hazardous waste handling systems, gas filtration systems,semiconductor devices (on-chip in situ getters) and spacecraft systems.

What is claimed is:
 1. A decontamination system having a porous, lightweight composite getter which collects particulate and molecularcontaminates, said getter comprising a three-dimensional metal meshmatrix having a porosity of 5-100 pores per inch, said metal mesh matrixbeing completely coated on the exterior surfaces thereof with alow-density porous aerogel having a density of 1-500 mg/cc, said getterbeing mounted in a gas duct for removing contaminants from gas flowingthrough said duct.
 2. The getter of claim 1 serving as a filter in aforced air duct for removal of airborne contaminants including dust,paint vapors, infectious viruses and molecules and hazardous waste. 3.The getter of claim 1 mounted in a duct between a source of gas withparticles and a vacuum chamber for filtering out certain size particlesor molecules from the gas flowing to said vacuum chamber.
 4. The getterof claim 3 wherein said gas is air containing biotechnicalmicro-organisms, at least some of which are filtered out before the airflows into said vacuum chamber.
 5. The getter of claim 3 wherein saidgas is silane gas containing particles including silica and SiH_(x), atleast some of which particles are filtered out from said gas by saidgetter.
 6. A decontamination system having a porous, light weightcomposite getter which collects particulate and molecular contaminates,said getter comprising a three-dimensional metal mesh matrix having aporosity of 5-100 pores per inch, said metal mesh matrix beingcompletely coated on the exterior surfaces thereof with a low-densityporous aerogel having a density of 1-500 mg/cc, said getter beingmounted in a photocopy machine, computer printer or FAX machine forcapture of toner fog and other contaminates.
 7. A decontamination systemhaving a porous, light weight composite getter which collectsparticulate and molecular contaminates, said getter comprising athree-dimensional metal mesh matrix having a porosity of 5-100 pores perinch, said metal mesh matrix being completely coated on the exteriorsurfaces thereof with a low-density porous aerogel having a density of1-500 mg/cc, which getter has a curved shape and is mounted in a tubularopen-ended housing for capture of contaminates from a gas passingtherethrough.
 8. The getter of claim 7 having a frustro-conical shapewith a getter mounted therein in the shape of a helix or Archimedesspiral.
 9. A decontamination system having a porous, light weightcomposite getter which collects particulate and molecular contaminates,said getter comprising a three-dimensional metal mesh matrix having aporosity of 5-100 pores per inch, said metal mesh matrix beingcompletely coated on the exterior surfaces thereof with a low-densityporous aerogel having a density of 1-500 mg/cc, which getter is mountedin places selected from the group consisting of operating rooms,cleanrooms, storage areas for surgical instruments, spacecraft, machinesand areas for manufacture of semiconductors.
 10. At least one getter ofclaim 9 being mounted proximate a stage for nanofabrication of amicrochip assembly microcircuit, for capture of particulate andmolecular contaminates that might otherwise contaminate saidmicrocircuit.
 11. The getter of claim 9 mounted near a semiconductorcircuit for capture of contaminates including offgassing contaminatesfrom the microchips in said circuit.
 12. The getter of claim 9 mountednear semiconductor wafers during manufacturing and later in use, forcollecting contaminates proximate thereto.